Method of and apparatus for recovering the by-products in the manufacture of fertilizer.



s. '0. MoGRATH.- METHOD OF AND APPARATUS FOR REGOVERING THE BY-PRODUGTSIN THE MANUFACTURE OF FERTILIZER.

APPLICATION FILED APR. 17, 1911.

Patented Feb. 10, 1914.

2 BHBETS-8HIEET 1.

%% xwa s. c; MdGRATH. mmnon 01? AND APPARATUS FOR REGOVERING THEBY-PRODUGTS IN THE MANUFACTURE or FERTILIZER. APPLICATION FILED APR. 17,1911.

' Patented Feb. 10, 1914.

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2 SHEETS-SHEET 2 a 541mm; (.772

COLUMBIA PLANDGRAPH CO.,WASHINGTON D. C.

wi -Z SAMUEL C. MCGBATH, OF BALTIMORE, MARYLAND, ASSIGNOB 9F NINE-TENTHSTO ALICE LIL-LIAN MCGRATH, OF BALTIMORE, MARYLAND.

METHOD OF AND APPARATUS FOR RECOVERING THE BY-PRODUCTS IN THESpecification of Letters Patent.

MANUFACTURE OF FERTILIZER.

Patented Feb. 10, 1914.

'0 all whom it may concern Be it known that I, SAMUEL C. MoGna'rn, acitizen of the United States, residing at Baltimore city, State ofMaryland, have invented new and useful Improvements in Methods of andApparatus for Recovering the By-Products in the Manufacture ofFertilizers, of which the following is a specification.

In the manufacture of fertilizer from fish scrap and othermaterials'well known for the purpose the gases evolved from the dryingof the material are allowed to escape into the atmosphere through anopen chimney which promotes a natural draft. This ar rangement resultsin a number of highly disadvantageous conditions. In the first place,these gases laden with ammonia are highly obnoxious and pollute theatmosphere for a distance of some miles. On this account it is notpractical to pursue the industry in a populous or even moderatelypopulated community. In the second place, the valuable products whichare bound up in the gases and which are, essentially, ammonia, theactive constituent of fertilizers and solid matter rich in ammonia, areallowed to escape and consequently there is a total loss of valuableby-products. In the third place it happens that there is a comparativelythick deposit of material on the lining of the chimney which has to beremoved from time to time and such removal is costly, not onlyintrinsically but because it necessitates the discontinuance of theoperation of the furnace or the battery of furnaces which are connectedto the chimney. Finally the arrangement is disadvantageous because thenatural draft frequently promotes the burning of the deposit of thematerial in the chimney and occasionally, even of the fish scrap orother material in the drier, and it is sometimes necesary to use a fireextinguishing apparatus to prevent the destruction of the material inthe drier and to avoid endangering the plant.

The objects of the present invention are to eliminate the disadvantagesnoted and the invention accordingly proposes a method of and apparatusfor treating the gases evolved from the drying of fish scrap and othermaterial which is to be understood as included, for the purposes of thisspecification,

I under the designation of fish scrap, whereby t-hese'gasesare finallyrendered innocuous or substantially so; the valuable solid and gaseousby-products are separated and separately recovered in a conditionenabling their commercial use without further treatment; and otherincidental disadvantages referred to in the foregoing paragraph areeliminated.

The method and apparatus constituting the present invention willbereadily understood by reference to the accompanying drawings, wherein IFigure 1 is a side elevation showing the furnace, the drier and theapparatus of the present invention in connection therewith;

Fig. 2 is a top plan view of the same; Fig.

3 is a detail longitudinal sectional view, the furnace being omitted;Fig. 4 is a cross section on the line M of Fig. 3; and Fig. 5 is a crosssection on the line 55 of Fig. 3.

Similar characters of reference designate corresponding parts throughoutthe several views. I

The furnace is shown at A (Figs. 1 and 2) and the rotary drier at B,these elements being of the ordinary construction. The fish scrap isdelivered to the drier by a suitable conveyor, shown diagrammatically atC. In the usual practice of the art the drier communicates with an openchimney or stack. According to the present invention, however, the driercommunicates with a closed chamber 1 which is of suit-able air tightconstruction. The gases which enter the chamber 1 pass in successionthrough a separating tank, an acid tank, and a sealing chamber. Tosecure this action a suction pump 2, having a gas outlet 2* is employed.The pump 2 creates a forced uniform draft which promotes combustion inthe furnace and which draws the gases through the various chambers andtanks referred to.

The separating tank is indicated by the numeral 3 and is of suitable airtight construction. The tank 3 is connected to the chamber 1 by a pipe 4which leads downwardly from said chamber. The gases enter the tank 3through the pipe 4 and during their travel pass through a body of water5 which partially fills said tank and said pipe. The water 5 may beobtained from any suitable source, although, in the interest of economy,the water which is extracted during the treatment of the fish in the oilpress may be employed, since such water is rich in ammonia and solidammonia-bearing particles.

It is preferred to provide two or more acid tanks. Two acid tanks areshown in the drawings and are indicated by the numerals 6 and 6respectively. These tanks are so arranged that one may be put in servicewhen the acid in the other is being renewed and consequently the renewalof the acid does not entail an interruption of the treatment oi thegases. The gases leave the tank 3 by a pipe 7 having two branches 8 and8 which lead to the tanks 6 and 6 respectively. A valve or damper 9 isprovided at the junction of the branches 8 and 8 and said valve ordamper, in accordance with its position, causes the gases to flow intoeither of the tanks 6 or 6 After leaving the acid tank the gases passinto a sealing chamber 10. If desired, two of these chambers may beemployed, as shown in Figs. 1 and 2, in which case the gases will passthrough them in succession. For convenience, only one chamber 10 isshown in Fig. 3, this being suiiicient to illustrate the principleinvolved. The connections between the tanks 6 and 6 and the adjacentchamber 10 comprises a pipe 11 which leads downwardly to said chamber10, and branches 12 and 12 which join with the pipe 11 and lead from thetanks 6 and 6 respectively. A valve or damper 13 is arranged at thejunction of the branches 12 and 12 to interrupt the communication ofeither of the tanks 6 or 6 with the pipe 11 when the acid of such tankis being renewed. From the sealing chamber or the last sealing chamberif there be more than one, the gases pass by way of a pipe 1st to thepump 2 and from the latter through the outlet 2 to any place or means offinal disposition or treatment.

The tanks 6 and 6 are supplied with acid from a reservoir 15 which issupported at a suitable elevation. The pipes which lead from saidreservoir to the acid tanks terminate near the tops of the latter anddeliver the acid as a falling spray through which the gases rise. A pipe16 leads from the reservoir 15 to the chamber 1 near the top 01 thelatter and within said chamber is provided with a suitable rose orperforated head to discharge the acid in the form of a spray. The acidthus discharged collects in a trough which is afforded by an inclinedshelf 17 and is conducted to the tank 6 or 6 by a pipe 18 havingbranches which lead to said tanks. Between the pipes 16 and 1.8 and at asuitable elevation a pipe 19 is arranged. This pipe 19 is preferablyprovided with a plurality of branches 20 which extend into the chamber 1and at its opposite ends itis provided with branches which lead to thetanks (3 and 6. The branches of the pipes 18 and 19 within the tanks 6and 6 have such extent as to be submerged in the acid in said tanks. Byvirtue of the provision of the pipe 19 a slight draft is created in theupper portion of the chamber 1 which causes the lighter portion of theammoniacal constituents of the gases to rise to the upper portion of thechamber and to pass through the branches 20 and the pipe 19. As thediverted portion of the gases pass through the spray delivered by thepipe 16 the ammonia is absorbed by the falling acid which collects onthe shelf 17 and is returned to the tank (5 or G as the case may be. Bythus separating a portion of the ammonia in advance of the passage ofthe gas through the separating tank, the percentage of moisture taken upby the gases in their passage through the separating tank and carriedover to the acid tank is considerably reduced and it follows that a toogreat dilution of the acid is prevented.

As the gases pass through the separating tan: 3 an ei'licient scrubbingaction is obtained and the suspended solid matters are precipitated andfall to the bottom of said tank. The recovery and treatment of the solidmatters thus deposited are important features of the invention and ameans for this purpose is herein shown by way of example. The lowerportion of the tank 3 has a trough shaped cross section and at itslowest point is formed with av channel 21 which partially incloses atransverse spiral conveyer The latter extends for a considerabledistance beyond the tank 3 and its eX- tended portion works in a tubularcasing 23 which forms, in effect, an axial continuation of the channel21. The casing 23 communicates with a casing 2t which disposed in avertical plane and incloses an endless belt conveyer The solid mattercarried by the conveyer 22 is delivered to the buckets of the conveyer25 which discharges such solid matter into a hopper 26. The lattercommunicates with a casing 27 which incloses a rotary screen 28,arranged to incline downwardly toward the chamber 1. The casing 27 isjoined to a second casing 2i which preferably has an upward inclinationand incloses a spiral conveyer 30 into which the solid matter not passedby the screen 28, is delivered. The liquid which is discharged throughthe screen 28 and which carries with it a small percentage of finesediment flows to a trap 31 arranged at the lowest point of the casing27 and from said trap is returned by a pipe to the casing 23. A suitabledrier 33 is arranged within the chamber 1. This drier may advantageouslycomprise a tubular casing 34 and a spiral. conveyer 35 working withinsaid casing 341.. The casing 29 is joined to the inlet end of the casing34. at the upper side of the latter so that the solid matterprecipitated in the tank 3 is ultimately carried through the casing 34:in which the drying of the recovered product is effected. The casing 34is of course heated by the gases which rise through the chamber 1 and toinsure the efficiency of this action a baffle plate 36 is provided whichdeflects the hot gases against the casing 34k and also prevents saidgases from having any substantial effect on the sulfate collected on theledge 17. The casing 34 discharges by way of an extension 37, shown indotted lines, which conducts the dried recovered solid matter to anysuitable receiver.

In practice the bulk of the dried fish scrap is removed from the drier Bby a conveyer 38 which is arranged adjacent the chamber 1. The gasespassing from the drier enter the chamber 1 wherein they are utilized todry the solid matter in the drier 33 and wherein a portion of theirlighter ammoniacal constituents are diverted and subjected to apreliminary acid treatment by the spray which discharges from the pipe16. The major portion of the gases leaves the chamber 1 through the pipe4 and rises through the water in the latter. The gases as they passthrough the tank 3 are efficiently scrubbed and solid particles carriedalong thereby are precipitated and carried to the drier 33 by the systemof conveyers described. The gases after rising through the water in thetank 3, pass to the tank 6 or 6 as the case may be, wherein they risethrough the body of acid in said tank and through the falling spray ofacid. In the manufacture of fertilizer a dilute solution of sulfuricacid is employed to absorb the ammonia and to produce ammonium sulfateand the acid may, when necessary, be drawn oil from time to time intosuitable vessels or carboys. The percentage of moisture which is carriedover from the tank 3 to the acid tank is materially reduced by virtureof the provision of the means for obtaining a preliminary acid treatmentin the chamber 1. Leaving the acid tank the gases pass through thesealing tank or tanks 10 wherein any acid carried over and any excess ofammonia is absorbed. The tank 10 serves not only as a final scrubbingmedium but also as a means to prevent the passage of acid to the pump 2and thus protects the latter. The gases, leaving the tank or tanks 10,are discharged by the pump 2 in an innocuous condition.

Having explained the method which constitutes the present invention anda suitable apparatus for carrying said method into effect, it may benoted that the chief advantages are the recovery of the valuableby-products and the discharge of the gas in an innocuous condition. Itis well known that the solid matters carried along by the gases are muchfiner and richer in ammonia and consequently of considerably greatercommercial value than the fish scrap which is removed from the drier.Heretofore, however, only such a percentage of the suspended solidmatter has been recovered as may have been deposited on the lining ofthe chimney; the rest of the suspended solid matter was allowed to go towaste; and the recoveryv of that deposit has been attended withconsiderable eX- pense. The present method provides for the recovery ofpractically all the suspended solid matter in a merchantable state andin an efficient and inexpensive manner and it provides also for theseparate recovery of the other valuable by-product, ammonia, in amerchantable state and in an equally eflicient and inexpensive manner.

It will of course be understood that any suitable means may be employedto keep the water in the tank 3 at the proper temperature. Sucharrangements are well known and form no part of the present invention;an illustration and description thereof is deemed unnecessary. Tocompensate for loss of water in the tank 3 any desired constant leveldevice, such as the well known float valve, may be employed.

It will be understood that no specific description herein contained isintended to put any limitation upon the scope of the appended claimswhich does not inhere in the language thereof.

Having fully described my invention, I claim:

1. A method of recoveringby-products from the gases of fish dryingfurnaces which comprise the steps of scrubbing the gases to removesuspended solid matters therefrom, collecting the solid mattersprecipitated during the scrubbing step, and utilizing the heat of thegases previous to their scrubbing treatment to dry the solid mattersrecovered.

2. A method of recovering by-products from the gases of fish dryingfurnaces which comprises the steps of scrubbing the gases to removesuspended solid matters therefrom, collecting the solid mattersprecipitated during the scrubbing step, subjecting the gases to acidtreatment for the recovery of ammonia after the scrubbing step, andutilizing the heat of the gases previous to their scrubbing treatment todry the solid matters recovered.

3. A method of recovering by-products from the gases of fish dryingfurnaces which comp-rises the steps of scrubbing the gases to removesuspended solid matters therefrom, collecting the solid mattersprecipitated during the scrubbing step, and utilizng the heat of thegases to dry the solid matters recovered.

4. A method of recovering by-products from the gases of fish dryingfurnaces which comprises the steps of diverting the lighter constituentsof the gases and subjecting them to an acid treatment, scrubbing theremainder of the gases, and subjecting the scrubbed to an acidtreatment.

5. A method of recovering by-products from the gases of fish dryingfurnaces which comprises the steps of diverting the lighter constituentsof the gases and subjecting them to a preliminary acid treatment,scrubbing the remainder of the gases, subjecting the scrubbed gases toan acid treatment, and subjecting the diverted gases to a second acidtreatment in connection with the acid treatment of the scrubbed gases.

(5. A method of recovering by-products from the of fish drying furnaceswhich comprises the steps of diverting the lighter constituents of thegases and subjecting them to a preliminary acid treatment, scrubbing theremainder of the gases, subjecting the scrubbed gases to an acidtreatment, subjecting the diverted to a second acid treatmentinconnection with the acid treatment of the scrubbed gases, collecting thesolid matters precipitated during the scrub bing step, and utilizing theheat of the gases previous to the scrubbing step to dry the solid matterrecovered.

7. An apparatus for recovering byproducts from the gases of fish dryingfurnaces which comprises a closed air tight chamber into which the gasespass, a scrubber to which the gases pass from the chamber, a drierarranged in the chamber, means for transferring the solid matterprecipitated in the scrubber tothe drier, and a pump for causing aforced draft and for drawing the gases through said chamber andscrubber.

8. An apparatus for recovering by-products from the gases of fish dryingfurnaces which comprises a closed air tight chamber into which the gasespass, a scrubber to which the gases pass from the chamber, a

drier arranged in the chamber, means for.

transferring the solid matter precipitated in the scrubber to the drier,an acid tank to which the gases pass from the scrubber, and a pump forcausing a forced draft and for drawing the gases through said chamber,scrubber and acid tank.

9. An apparatus for recovering by-prodacts from the gases of fish dryingfurnaces which comprises a scrubber connected. to the furnace and intowhich the gases pass, a drier arranged to be heated by the flowinggases, and means for collecting the solid matter precipitated in thescrubber and for transferring said solid matter to said drier.

10. An apparatus for recovering by-prodacts from the gases of fishdrying furnaces which comprises an air tight chamber into which thegases pass, a scrubber into which the gases pass from the chamber, adrier arranged within the chamber, means for transferring the solidmatter precipitated in the scrubber to the drier, an acid tank to whichthe gases pass from the .crubber, a sealing chamber to which the gasespass from the acid tank and a pump for drawing the gases through saidair tight chamber, scrubber, acid tank and scaling chamber.

11. An apparatus for recovering by-products from the gases of fishdrying furnaces which comprises an air tight chamber into which thegases pass, a scrubber into which the gases pass from the chamber, adrier arranged within the chamber, means for transferring the solidmatter precipitated in the scrubber to the drier, an acid tank to whichthe gases pass from the scrubber, a sealing chamber to which the gasespass from the acid tank, an acid reservoir for supplying the tank, apipe extending between the reservoir and the air tight chamher andprovided with a rose in the latter, a shelf upon which the acid sprayedfrom the rose collects, a pipe for conveying the acid which collects inthe shelf to said acid tank, and a pump for drawing the gases throughsaid air tight chamber, scrubber, acid tank and sealing chamber.

In testimony whereof I have hereunto set my hand in presence of twosubscribing witnesses.

SAIYIUEL C. MCGRATH. Witnesses JOHN L. Pownns, H. L. MAOCARTENY.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, I). C.

